Cutting device for warp-knitted fabrics

ABSTRACT

The cutting device is equipped with a feeding device ( 10 ) for a warp-knitted fabric ( 4 ). The warp-knitted fabric has at least two warps ( 6 ), between which floating weft yarns ( 8 ) are placed. The cutting device is also equipped with a cutting implement ( 22 ) for cutting through the weft yarns ( 8 ) and with a leading away device ( 24 ) for the severed warps ( 6 ) that serve as effect yarns. In order to improve the cutting device, the cutting implement ( 22 ) comprises guide elements ( 32, 34 ) with projecting guide edges ( 36, 38 ) serving to support the weft yarns ( 8 ) to be cut. The guide edges ( 36, 38 ) form a gap ( 40 ) between them into which a rotating blade ( 42 ) extends. The guide elements ( 32, 34 ) also contain, on the sides facing away from the guide edges ( 36, 38 ), rebouncing guide surfaces ( 44, 46 ) for the warps ( 6 ).

TECHNICAL FIELD

The invention relates to a cutting device for warp-knitted fabricsaccording to the preamble of claim 1. Effect yarns, which are alsodesignated as fancy yarns, can be produced by means of such a cuttingdevice.

PRIOR ART

Cutting devices of the type initially mentioned are known. In this case,the cutting device is arranged directly on the knitting machine betweenthe knitting head and a band take-up. The cutting devices are equippedeither with shears or with a knife. The known cutting devices are, onthe one hand, complicated and, on the other hand, difficult to handleand do not provide effect yarns of high quality.

PRESENTATION OF THE INVENTION

The object of the invention is to improve a cutting device of the typeinitially mentioned.

The object is achieved, according to the invention, by means of thecharacterizing features of claim 1.

Since the cutting implement has guide members with projecting guideedges for supporting the weft threads of a warp-knitted fabric which areto be cut, the guide edges forming between them a gap for the engagementof a rotatable knife, an exact guidance of the weft threads to be cut,on the one hand, and a reliable engagement of the rotatable knife, onthe other hand, are ensured. In this case, the weft threads areoptimally tensioned, in particular, by means of the guide surfaces forthe knitted warps, said guide surfaces being set back laterally withrespect to the guide edges, and thus assist a satisfactory cutting ofthe weft threads by the rotatable knife. The cutting device has a simpleconstruction, allows simple operation and provides satisfactory effectyarns.

The cutting device may be integrated in a knitting machine, in whichcase the feed device and the discharge device may be part of theknitting machine. This is more advantageous however, when the cuttingdevice is designed as an independent unit independently of a knittingmachine. The cutting device can then be operated separately from theknitting machine, the advantage of this being that, on the one hand, itis more easily accessible and, on the other hand, optimum utilizationbecomes possible, since the cutting device can cut substantially morequickly than the knitting machine can knit. An independent cuttingdevice therefore has a substantially higher output than a knittingmachine. Moreover, a separate cutting device affords the advantage thatthe knitting process of a knitting machine is not interrupted by anycutting errors which occur. Furthermore, where a separate cutting deviceis concerned, there is no need to allow for structural restrictionswhich are due to an arrangement in a knitting machine.

Advantageous embodiments of the cutting device are defined in claims 2to 12.

In principle, the guide members of the cutting implement may be designedas sliding bodies past which the warp-knitted fabric to be separatedslides. The embodiment as claimed in claim 2 is more advantageous,however, according to which the guide members are designed as rotarybodies which assist the flow of movement of the warp-knitted fabricalong the knife. In this case, it is advantageous if those regions ofthe guide members which are adjacent to the guide edges are designed toprevent slip, that is to say have an antislip region, in order toimprove the driving of the guide members designed as rotary bodies.According to claim 3, the antislip region may have a coating consistingof rubber. According to claim 4, an embodiment with a roughened surfaceor with a rough-coated surface, for example a surface coated withcorundum, is also possible. The embodiment as claimed in claim 5 isparticularly advantageous, however, according to which the antislipregion is provided with a toothed ring. If appropriate, it may beexpedient to provide the rotatable guide members with a drive.

The knife may be freely rotatable. It is more advantageous, however, if,according to claim 7 it can be driven by means of a motor at acircumferential speed which is higher than the running speed of thewarp-knitted fabric. It may be expedient if the direction of rotation ofthe rotating knife is opposite to the running direction of thewarp-knitted fabric, but a direction of rotation in the runningdirection of the warp-knitted fabric is more advantageous.

An embodiment of the cutting device as claimed in claim 8 isparticularly advantageous, according to which both the feed device andthe discharge device have cambered guide members, the setback parts ofwhich serve for receiving the knitted warps. As a result, on the onehand, an optimum feed of the warp-knitted fabric to the cuttingimplement and, on the other hand, an optimum discharge of the effectyarns obtained by means of the separated warps are possible. These guidemembers may be sliding guides, but the design as claimed in claim 9 asrotatable guide members is more advantageous. According to claim 10, thefeed device is designed as a tension device. According to claim 11, thedischarge device expediently has a take-up roller.

A particularly advantageous cutting device is obtained when, as claimedin claim 12, the cutting implement has arranged after it a guide combwhich engages between the warps and which can be moved back and forth ina controlled manner transversely with respect to the running directionof the warps. It is thereby possible to control the cutting point alongthe weft threads so that warps serving as effect yarns and havingfringes of varying lengths can be produced. The effect properties of theeffect yarns can thus be further varied.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are described in more detailbelow with reference to the drawings in which:

FIG. 1 shows a cutting device for warp-knitted fabrics in a diagrammaticillustration;

FIG. 2 shows a cutting region of the cutting device in a verticalsection transversely with respect to the running direction of thewarp-knitted fabric.

WAYS OF IMPLEMENTING THE INVENTION

FIGS. 1 and 2 show a cutting device for warp-knitted fabrics 4 for theproduction of effect yarns 2. The warp-knitted fabric 4 has at least twoknitted warps 6, between which floating weft threads 8 are arranged. Inthe simplest instance, the warp-knitted fabric may consist, asillustrated, of two warps 6 and of weft threads 8 lying between them. Asa rule, however, the warp-knitted fabric 4 will have a greater widthwith numerous warps which are connected to one another by means offloating weft threads.

The warp-knitted fabric 4 is fed via a feed device 10 which is formed bya tension roller 12 and a deflecting roller 14 which in each case havecambered guide portions 16. The weft threads 8 in this case lie abovethe projecting part 18 and the warps 6 in the setback parts 20. Thewarp-knitted fabric runs through a cutting implement 22 in which theweft threads 8 are severed, the separated warps then being taken up aseffect yarns by a discharge device 24. The latter contains a guideroller 26 with cambered guide portions 28 which are designed in asimilar way to the cambered guide portions 16 of the tension roller 12or of the deflecting roller 14. The effect yarns 2 are then dischargedby a downstream take-up roller 30.

The cutting implement 22 contains guide members 32, 34 with projectingguide edges 36, 38 which form between them a gap 40 into which arotatable knife 42 engages. The knife 42 may be freely rotatable, but ispreferably connected to a drive motor, not illustrated in any moredetail, which imparts to it a cutting speed, preferably in the runningdirection of the warp-knitted fabric 4, which is higher than the runningspeed of the warp-knitted fabric. The guide members 32, 34 are provided,on the sides facing away from the guide edges 36, 38, with setback guidesurfaces 44, 46 for the warps 6. The guide members 32, 34 together forma cambered supporting surface for the warp-knitted fabric to be cut. Bymeans of the setback guide surfaces 44, 46, the warps 6 arepre-tensioned into the setback part and thereby tension the weft threads8 connecting them, across the gap 40, thus affording optimum conditionsfor satisfactory cutting by the rotating knife 42.

The guide members 32, 34 may be sliding guides, but they areadvantageously designed as rotating guide members which are freelyrotatable. In this case, it is expedient if the regions adjacent to theguide edges 36, 38 are designed as antislip regions 48, thus assistingthe driving of the guide members by the warp-knitted fabric moved past.The antislip region has, for the reliable driving of the guide members32, 34, a toothed ring 50, the teeth 52 of which engage between the weftthreads 8, thereby achieving an optimum driving of the rotatable guidemembers 32, 34.

The cutting implement has arranged after it a guide comb 54 whichengages between the separated warps and which can be moved back andforth in a controlled manner transversely with respect to the runningdirection of the warps in a way not illustrated in any more detail. Itis thereby possible for the warp-knitted fabric which is to be cut to beoffset at the guide members laterally within a specific scope, with theresult that the cutting point of the knife at the weft threads 8 can beoffset. The effect yarns can therefore be produced with fringes 56 ofchanging length.

LIST OF REFERENCE SYMBOLS

-   2 Effect yarn-   4 Warp-knitted fabric-   6 Warp-   8 Weft thread-   10 Feed device-   12 Tension roller-   14 Deflecting roller-   16 Cambered guide portion-   18 Projecting part-   20 Setback part-   22 Cutting implement-   24 Discharge device-   26 Guide roller-   28 Cambered guide portion-   30 Take-up roller-   32 Guide member-   34 Guide member-   36 Guide edge-   38 Guide edge-   40 Gap-   42 Knife-   44 Guide surface-   46 Guide surface-   48 Antislip region-   50 Toothed ring-   52 Tooth-   54 Guide comb-   56 Fringe

1. A cutting device for warp-knitted fabrics, with a feed device for thewarp-knitted fabric which has at least two warps, between which floatingweft threads are arranged, furthermore with a cutting implement forcutting through the weft threads, and with a discharge device for theseparated warps serving as effect yarns, characterized in that thecutting implement has guide members with projecting guide edges forsupporting the weft threads to be cut, the guide edges forming betweenthem a gap for the engagement of a rotatable knife, further of the guidemembers having, on the sides facing away from the guide edges, setbackguide surfaces for the warps.
 2. The cutting device as claimed in claim1, characterized in that the guide members of the cutting implement aredesigned as rotary bodies, at least those regions of the guide memberswhich are adjacent to the guide edges being designed to prevent slip. 3.The cutting device as claimed in claim 2, characterized in that theantislip region has a coating consisting of rubber.
 4. The cuttingdevice as claimed in claim 2, characterized in that the antislip regionhas a roughened or rough-coated surface.
 5. The cutting device asclaimed in claim 2, characterized in that the antislip region isprovided with a toothed ring.
 6. The cutting device as claimed in claim2, characterized in that the rotatable guide members are provided with adrive.
 7. The cutting device as claimed in claim 1, characterized inthat the rotatable knife is assigned a drive.
 8. The cutting device asclaimed in claim 1, characterized in that the feed device and dischargedevice have cambered guide portions, the setback parts of which servefor receiving the warps.
 9. The cutting device as claimed in claim 8,characterized in that the guide portions are designed rotatably.
 10. Thecutting device as claimed in claim 9, characterized in that the feeddevice is designed as a tension device.
 11. The cutting device asclaimed in claim 1, characterized in that the discharge device has atake-up roller.
 12. The cutting device as claimed in claim 1,characterized in that the cutting device has arranged after it a guidecomb which engages between the separated warps and which can be movedback and forth in a controlled manner transversely with respect to therunning direction of the warps.
 13. The cutting device as claimed inclaim 2, characterized in that the rotatable knife is assigned a drive.14. The cutting device as claimed in claim 2, characterized in that thefeed device and discharge device have cambered guide portions, thesetback parts of which serve for receiving the warps.
 15. The cuttingdevice as claimed in claim 2, characterized in that the discharge devicehas a take-up roller.
 16. The cutting device as claimed in claim 2,characterized in that the cutting device has arranged after it a guidecomb which engages between the separated warps and which can be movedback and forth in a controlled manner transversely with respect to therunning direction of the warps.
 17. The cutting device as claimed inclaim 3, characterized in that the rotatable knife is assigned a drive.18. The cutting device as claimed in claim 3, characterized in that thefeed device and discharge device have cambered guide portions, thesetback parts of which serve for receiving the warps.
 19. The cuttingdevice as claimed in claim 3, characterized in that the discharge devicehas a take-up roller.
 20. The cutting device as claimed in claim 3,characterized in that the cutting device has arranged after it a guidecomb which engages between the separated warps and which can be movedback and forth in a controlled manner transversely with respect to therunning direction of the warps.